The work involves studying in precise chemical terms how genes are regulated. For such investigations, we have chosen the lac operon of E. coli and the major leftward/rightward promoters in bacteriophage lambda. These operator DNAs have been chemically synthesized. Furthermore, several mutated operators are being prepared. In addition, BrdU has been inserted at several specific sites. All of these operators will be used for studies on how lac and lambda repressors interact with their respective operator DNAs. Other studies will involve sequencing spacer regions in S5 DNA from HeLa cells. The procedure involves use of a chemically synthesized deoxyoligonucleotide presently synthesized. This deoxynucleotide is complementary to the 5'-end of S5 RNA and will be used to carry out primer dependent repair synthesis into the S5 DNA spacer region. BIBLIOGRAPHIC REFERENCE: Caruthers, M.H., Goeddel, D.V., and Yansura, D.G. (1975) Federation Proceedings Abstract: 34:1891.